The 7300 FX has a rigid fork, while the 7300 has a front suspension. Also, I believe the 7300 FX has grip shifters, while the 7300 has rapid-fire shifters. The 7300 is also a bit more expensive, but not by much. I tend to prefer a front suspension, so I'd choose the 7300 over the 7300 FX.

They are indeed both good bikes. I was just looking at them recently at the LBS, and they recommended the 7300 or 7300 FX for riding both roads and trails. They actually recommended it over the 7500 for basic riding, saying that while the 7500 has better components, it's not worth the extra money for simple recreational use.